1. Field of the Invention
The present invention relates to a land grid array (LGA) connector assembly, and particularly to an LGA connector assembly with a foldable retention device for retaining a heat sink upon an LGA package mounted on an LGA connector.
2. Description of Related Art
IC packages having leads arranged in a land grid array (LGA) are well known as LGA packages. Connectors for removably mounting LGA packages on printed circuit boards (PCBs) are known as LGA sockets which are introduced in the internet website address: http://www.kns.com/prodserv/test-division/products/sockets/BGA-LGA. asp. An LGA socket as described in U.S. Pat. Nos. 5,282,111, 5,485,351 and 5,702,256, comprises a substantially flat insulative housing defining an array of passageways with electrical contacts received therein corresponding with the array of leads of a mating LGA package. Each contact has a pair of free ends oppositely projecting beyond external surfaces of the socket housing for respectively engaging with corresponding contact pads respectively on a bottom surface of the LGA package and on a top surface of the PCB. To dissipate the heat generated by an IC chip incorporated in the LGA package, a heat sink is commonly applied.
Different devices are disclosed by the prior art for clamping the LGA package, the LGA socket and the PCB together, thereby establishing an electrical connection between the contacts of the LGA socket and corresponding contact pads of the LGA package and the PCB. U.S. Pat. No. 4,906,194 discloses an LGA package assembly consisting of an upper support clip, an LGA package, an LGA socket, a PCB, an insulator, and a lower support clip. The components of the LGA package assembly are fastened to each other by a plurality of threaded screw members sequentially extending through bores defined in each component. Therefore, an assembling of the LGA package assembly is laborious and tedious. U.S. Pat. No. 5,847,928 discloses another LGA package assembly consisting of a heat sink, an LGA package, an LGA socket and a PCB. The components are fastened together by a clip disposed on a bottom side of the PCB which has two upwardly extending arms inserted in aligned apertures of the PCB and the heat sink. One problem with this design is that the retention force of the clip for fastening the components of the assembly together is not sufficient enough to prevent physical separation therebetween when the assembly is subject to external shock and vibration. Such a physical separation may result in broken circuits between the LGA package and the PCB, thereby adversely affecting the operation of the LGA package assembly.
Hence, an improved retention device for an LGA connector assembly is required to overcome the disadvantages of the conventional retention device.
Accordingly, an object of the present invention is to provide a retention device which is foldable to have a lower profile for lowering the shipment cost.
A further object of the present invention is to provide a retention device which can securely fasten an LGA socket, an LGA package, a heat sink module and a printed circuit board together.
Still an object of the present invention is to provide a retention device which can be easily operated to press in sequence a heat sink module, an LGA package and an LGA socket to a printed circuit board.
In order to achieve the objects set forth, a retention device of the present invention comprises a main frame, a spring clip, a pair of front pivots, a pair of rear pivots and an actuating lever. The front and rear pivots are pivotably assembled to the main frame. The spring clip is pivotably attached to the rear pivots, and comprises a downward extending pressing portion for pressing against a heat sink module and a receiving arm extending forwardly from a front end of the pressing portion. The actuating lever is pivotably attached to the front pivots and rotated to lock the receiving arm of the spring clip. Therefore, the spring clip may exert a downward force upon the heat sink module toward an LGA package and securely retain the heat sink module and the LGA package upon an LGA socket which is in turn pressed to a printed circuit board. While the heat sink module and LGA package are not accommodated in a chamber of the main frame, the actuating lever and the spring clip can be removed from the front and rear pivots, whereby the front and rear pivots are rotated/folded to a horizontal position to reduce the profile of the retention device.